As hundreds of thousands of readers already know, The First 90 Days is a road map for taking charge quickly and effectively during critical career transition periods—whether you are a first-time manager, a mid-career professional on your way up, or a newly minted CEO. Indeed, the practical methodology depicted in the perennial best-selling business resource has helped untold numbers of people as they take on the challenges of a new role.

Given the overwhelmingly positive reviews, we thought we would take the opportunity of the holiday season to give you a chance to win two copies of The First 90 Days signed by the author—onboarding expert, Michael Watkins.

All you have to do is re-tweet using #FIRST90holiDAYS and tell us in ten words or less: What was the biggest challenge you faced during the first 90 days of your most recent career transition?

Entries will be accepted beginning on Monday, December 4th and will close on Thursday, December 7th. The winner will be announced on Friday, December 8th.

GOOD LUCK!

Meanwhile, over on Harvard Business Review’s Facebook Page, our co-founder and author of The First 90 Days, Michael Watkins, is hosting a “Career Chat” with Harvard Business Review subscribers all week long.

As a starting point, Michael shared with HBR four lessons on what NOT to do when you start a new job.

1) Don’t ignore the culture

A new team may have a different approach to success, teamwork, and individualism than you are accustomed to. Michael says, “When new leaders act in ways that are inconsistent with the culture, they risk building resistance.” For example, you should pay close attention to what your new team considers a “win.” How is individual success viewed: as an accomplishment or as grandstanding that detracts from the team’s success?

2) Don’t jump to conclusions

A new leader may enact changes too quickly because of a need to appear decisive and authoritative. Michael says, “Too many arrive on the scene with ‘The Answer’ – a preordained fix for the organization’s problems.” But employees may resent a leader who handles problems based on a superficial understanding of their situation. Instead of making up your mind immediately, Michael recommends cultivating an “ability to learn the true nature of the situation.”

3) Don’t keep mediocre team members

Although you should take your time to deeply consider the team’s challenges, you shouldn’t ignore a gut feeling that an employee is not the right fit. “Leaders are brought in to improve performance by imparting new ideas, making tough decisions and instilling a can-do spirit of achievement,” Michael says. You may hope that your leadership can change a direct report’s poor performance, but some employees “are too inflexible to change,” Michael cautions. Don’t wait to replace team members who aren’t up to standards.

4) Don’t forget about your peers

When you step into a new leadership role, you’ll spend most of your time with your “vertical” colleagues, your direct reports and your bosses. But you should also cultivate “horizontal” relationships. “Sooner or later (probably sooner),” Michael says, “new leaders need the support of people who aren’t under their authority.” Making connections with your fellow leaders and with “key external constituencies” is a crucial part of your first weeks in a new job.